The invention relates to a tensioning device for a traction mechanism drive which is disposed on an internal combustion engine and has a drive wheel arranged on a drive shaft of a machine, one or more additional driving wheels and a continuously revolving traction means which wraps around the drive wheel and the additional driving wheels. The tensioning device comprises two tensioning arms, having tensioning wheels which are mounted thereon and apply tensioning force to the traction means in front of and behind the drive wheel in the direction of revolution, and has a spring means, which generates the tensioning force, and a tensioner housing, which movably supports at least one of the tensioning arms subjected to the force of the spring means.
Particularly in traction mechanism drives having driving wheels which alternately take up and deliver torque, and having a corresponding alternation of tight strand and slack strand, the tensioning of the slack strand calls for a tensioning device having two tensioning wheels which pretension the traction means in front of and behind the drive wheel of the alternately driving and driven drive shaft. The drive shaft is constituted typically and not necessarily by the shaft of the machine configured as a starter generator, which machine delivers torque for the starting of the internal combustion engine and takes up torque for the generation of current.
While the traction mechanism drives can basically be constituted by belt, chain or link conveyor drives, tensioning devices of the type stated in the introduction are typically known as belt tensioners in an ancillary unit belt drive in a variety of designs. In DE 199 26 615 A1, DE 10 2008 025 552 A1 and DE 10 2006 019 877 A1, for instance, are proposed tensioning devices which respectively have a tensioner housing, which is fastened to the starter generator, and two tensioning arms, which are mounted movably therein and the tensioning rollers of which are forced closer together by an intermediate spring means in order to tension the belt.